title: Tailored covalent grafting of hexafluoropropylene oxide oligomers onto silica nanoparticles: toward thermally stable, hydrophobic, and oleophobic nanocomposites.
abstract: The modification of silica nanoparticles with hexafluoropropylene oxide (HFPO) oligomers has been investigated. HFPO oligomers with two different average degrees of polymerization (DPn = 8 and 15) were first prepared by anionic ring-opening polymerization, deactivated by methanol, and in some cases postfunctionalized by aminopropyl(tri)ethoxysilane or allylamine. The "grafting onto" reactions of these oligomers were then carried out either on bare silica (reaction between a silanol surface and ethoxy-silanized HFPO) or on silica functionalized by amino groups (in an amidation reaction with methyl ester-ended HFPO) or mercapto groups (via the radical addition of allyl-functionalized HFPO). Hybrid nanoparticles thus obtained were characterized by solid-state (29)Si NMR and FTIR spectroscopies as well as elemental and thermogravimetric analyses. The results assessed a significant yield of covalent grafting of HFPO oligomers when performing the hydrolysis-condensation of ethoxylated HFPO on the bare silica surface, compared to the other two methods that merely led to physically adsorbed HFPO chains. Chemically grafted nanohybrids showed a high thermal stability (up to 400 °C) as well as a very low surface tension (typically 5 mN/m) compared to physisorbed complexes.
authors.affiliation: Institut Charles Gerhardt, Ingénierie et Architectures Macromoléculaires, UMR CNRS 5253, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue de l'Ecole Normale, 34296 Montpellier, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Durand
authors.forename: David
authors.initials: D
authors.lastname: Mariot
authors.forename: Bruno
authors.initials: B
authors.lastname: Améduri
authors.forename: Bernard
authors.initials: B
authors.lastname: Boutevin
authors.forename: François
authors.initials: F
authors.lastname: Ganachaud